Antisiphon lap joint for building sheets

Abstract

A building sheet suitable for roofing and siding provides a weatherproof lap joint having an antisiphon gap when installed partially overlapping an adjacent like building sheet by spacing the entire overlapping portion of one sheet above the lapped portion of an adjacent sheet. Parallel strengthening ribs formed into the building sheet are structurally modified along one edge to form an overlapping member and along the opposite edge to form a lapped member. The overlapping member includes an intermediate strengthening bead and an exterior downwardly projecting sealing lip which rests upon the lapped member of an adjacent sheet and spaces the entire overlapping member of one sheet above the lapped member of the adjacent sheet. The force created by fasteners securing the flat portions of the sheets to the underlying structure is transferred through the overlapping member, due to its being entirely separated from the lapped member, and focuses downward pressure at the sealing lip causing it to resiliently deform and achieve a tight seal while maintaining the antisiphon gap. Low sills, alternating in a parallel array with the ribs, add strength to the sheet, as does the bead incorporated into the margin of the overlapping member and a small angled fastening flange along the edge of the lapped member which also provide additional rigidity to these edges.

What is claimed is: 
     
       1. A lap joint construction for forming a tight weatherproof juncture between partially overlapping adjacent building sheets for roofing and the like, comprising: (a) a lapped member including a rib extending along the entire extent of the juncture, said rib including a pair of upwardly-converging sloping sidewalls interconnected by a table;   (b) an overlapping member including an inner section having a shape which is congruent with the shape of a portion of said lapped member, a sealing lip arranged to resiliently separate the entire extent of said overlapping member from said lapped member when said overlapping member is urged toward said lapped member, and an intermediate strengthening bead interfacing said sealing lip with the remainder of said overlapping member; and   (c) fastening means for tightly securing said lapped and said overlapping member to an underlying structure and for urging said overlapping member toward said lapped member;   (d) said fastening means being located on the sheet apart from said lapped and overlapping members.   
     
     
       2. A lap joint according to claim 1 wherein said sealing lip contacts one of said sloping side walls of said lapped member intermediate the height thereof when said overlapping member is positioned over said lapped member. 
     
     
       3. The lap joint according to claim 1 including an exterior fastening flange attached to and extending along the outer edge of said rib. 
     
     
       4. A lap joint according to claim 3 wherein said fastening means is placed through the sheet, immediately ajacent to said fastening flange, and tightly secured to an underlying structure. 
     
     
       5. A generally planar building sheet suitable for roofing and siding, said sheet comprising: (a) a plurality of parallel spaced-apart basic ribs separated from one another by planar panels;   (b) said basic ribs having upwardly-converging side walls interconnected by a table;   (c) a lapped member extending along one margin of this sheet, said lapped member including one of said basic ribs;   (d) an overlapping member extending along the opposite margin of this sheet, said overlapping member including an inner portion of one of said basic ribs and an exterior sealing lip attached to said inner portion of said basic rib along the edge thereof;   (e) an intermediate strengthening bead interconnecting said inner portion of said basic rib and said sealing lip;   (f) said sealing lip situated at a suitable angle for spacing said entire overlapping member above said lapped member of a similar adjacent sheet when said overlapping member is resiliently urged downwardly upon said lapped member.   
     
     
       6. A building sheet according to claim 5 wherein said sealing lip terminates intermediate the height of said lapped member. 
     
     
       7. A building sheet according to claim 5 wherein said inner portion of one of said basic ribs includes the inner one of said upwardly-converging side walls, said table, and the upper portion of the outer one of said upwardly-converging side walls. 
     
     
       8. A building sheet according to claim 5 wherein said sealing lip is situated at an angle 10° nearer to perpendicular to the plane of the sheet than is said sloping side wall of said lapped member. 
     
     
       9. A building sheet according to claim 5 wherein said lapped member includes an exterior fastening flange attached to and extending along the base of said basic rib. 
     
     
       10. A building sheet according to claim 9 wherein said fastening flange is inclined upwardly from the plane of the sheet and extends outwardly from the base of said basic rib. 
     
     
       11. A building sheet of claim 10 wherein said fastening flange is inclined at an angle of 10° from the plane of the sheet. 
     
     
       12. A building sheet according to claim 5 wherein said intermediate strengthening bead comprises a C-shaped ridge integrally attached by its margins to said inner portion and said sealing lip.